Whatever you do, walk up steep hills and spin up gentle ones until you get this fixed. No hard sprints on the flat either, and don't stand up on the pedals for a stretch
This is partly to avoid injury if it fails suddenly with your weight on it, but also to reduce stress on the interface. Every time it goes it will get worse and even once more might total it.
Looking on a big screen I maybe have some good news for your trip - only half the length of the splines in the crank arm looks stripped. You can see on the axle as well that the outer half of the splines has aluminium on there. That almost certainly means it was loose for some time, and went when only about 50% engaged. If you're really gentle, the remaining 50% should get you home. You might not even need a new BB.